#188: On Infantile Spasms and Seizures

August 12, 2026 | By Sam Masur

Audio

Have you ever wondered when exactly you should be getting an EEG to capture an unusual baby movement? Featuring pediatric epileptologist Dr. Eva Catennacio of the Children’s Hospital of Philadelphia, this episode focuses on the intricacies of an infantile spasms syndrome diagnosis. Tune in to learn when to order an EEG, how to diagnose infantile spasms, and the benefits of early effective treatment. 

Infantile Spasms Pearls

1. Evaluate early: If uncertain whether a certain presentation is seizure or not, there is a low threshold to refer for further evaluation and EEG.
2. Treat quickly: The goal is early, effective treatment for infantile spasms within the first few weeks of presentation.
3. Follow-up frequently: Patients should follow-up frequently after diagnosis to make sure the child is responding to treatment.
4. Prognosis is dependent on etiology: Ultimately, prognosis for infant spasms is driven by underlying etiology.

Final infographic to be added here

Infantile Spasms Notes 

Abnormal Movements

Signs of Infantile Seizures:

The following are signs associated with a higher risk of infantile seizures

1. Focal, rather than generalized, movements
2. Movements that are stereotyped, or the same every single time 
3. Abnormal movements that occur during the sleep-wake transition
4. Loss of developmental skills
5. Dr. Catenaccio’s expert opinion: No association with excitement (i.e. while eating or in their high chair)

Clinical Pearls:

• Both untrained and highly trained people have been shown to have difficulty identifying infantile seizures and so when in doubt, you should consider getting an EEG!

• Home videos have revolutionized pediatric neurology – when concerned, have a parent take a video of the event.
• The neurologic exam is helpful to determine seizure risk, but less helpful in determining whether a movement was a seizure
• A thorough skin exam may be helpful given that some neurocutaneous disorders have associated skin findings (i.e. tuberous sclerosis with ash leaf spots)

EEG

Electroencephalography (EEG) is a brainwave test utilizing electrodes on the scalp that measure brain electrical activity. EEG can characterize an abnormal movement as seizure vs. not-seizure, characterize baseline background brain activity, and assess for interictal (between seizure) abnormalities. Ideally, an EEG would capture sleep-wake cycles to assess for ictal activity in that transition period.

• Routine or spot EEGs do not typically capture sleep unless they’re under 1 years old. They can be helpful if you have a very low index of concern. Your institution may have something called a four hour EEG.
• The characteristic finding on EEG for infantile spasms is something called hypsarrhythmia which is a pattern of disorganized high amplitude, high voltage brain activity with multifocal abnormal epileptiform discharges. 

Infantile Epileptic Spasms Syndrome (prev called West Syndrome)

This syndrome was first described by Dr. WJ West in 1841, which he named after his son who had the syndrome.

Clinical Criteria:

1. Infantile spasms, which are a subset of a type of seizure called epileptic spasms.
   1. Infantile spasms are epileptic spasms that typically occur between the ages 6 months-2 years old. 
   2. An age and developmental phenomenon. It’s unclear why they happen, as many different etiologies can lead to infantile spasms; it’s likely the way brain injury and brain development in this specific age window interact.
2. EEG pattern of hypsarrhythmia
3. Developmental arrest or regression

You don’t have to have all three to have the syndrome, and especially if recognized very early, they may not have progressed to having hypsarrhythmia or developmental arrest.

Work-up of infantile epileptic spasms syndrome

1. EEG for hypsarrhythmia
2. MRI brain to assess for structural reasons that could lead to infantile spasms, including Tuberous Sclerosis.
   1. Urgency is high. Goal to get it within days to 1-2 weeks
3. Genetic testing, usually whole exome sequencing

Treatment

Treating quickly yields the best outcomes and can arrest or reverse the developmental regression

ACTH or Prednisolone

Prednisolone

• Dr. Catenaccio’s expert opinion: more effective, easier to administer, and cheaper than ACTH.
• Dosing: based on the UKISS protocol (J Paediatr Child Health, 2022)
• Usually single course, but for patients who respond well to steroids but relapse, some practitioners do another pulse dose of steroids.

ACTH

• Similar to a steroid 
• Dosing: based on body surface area (there is an online calculator for dosing).

Side effects for both ACTH and prednisolone are increased appetite, immunosuppression, potentially increased bleeding risk, hypertension, hyperglycemia, and irritability

Vigabatrin

• Anti-seizure medication initially used in adults but found to be effective for infantile spasms, specifically for children with tuberous sclerosis.
• Dosing: typically 150 mg/kg/day divided two times daily. Will treat for at least 6-12 months given
• Dr. Catenaccio’s expert opinion: lower relapse risk with longer treatment.
• Side effects: sleepiness, low tone, and retinal injury with extended exposure. Patients are part of a program called REMS where they are referred to ophthalmology for recurrent vision exams while on medication. Vigabatrin can also impact MRI results and can mimic a metabolic disease on MRI. 

Adjusting Therapies

• Although the data is controversial, in general, prednisolone and ACTH are slightly more effective than vigabatrin EXCEPT in the tuberous sclerosis population
• Dr. Catenaccio will use prednisolone as a first-line unless there is a contraindication or she suspects a fixed etiology that will likely be persistent. Prednisolone has higher likelihood of relapse (since the course is only 1 month) and sometimes, she will choose vigabatrin because it can be given for longer.
• Rapid sequential therapy (Neurology, 2022) shows that 80% of patients who are going to respond to a medication respond within the first week; therefore, if spasms are still ongoing after the first week, you can switch to a different first-line therapy.
• Benzodiazepine rescues are usually not recommended, even for prolonged clusters of spasms. Spasms do not typically lead to respiratory compromise. 
• For children who are not responding to standard treatments with focal causes (ex: focal cortical dysplasia, hemimegancephaly, perinatal stroke), they may be candidates for epilepsy surgery. If spasms are refractory, they should proceed to epilepsy surgery rapidly. Corpus callostomy (division of the corpus callosum) is increasingly used to treat refractory spasms, although there isn’t much data to support how it will help with developmental outcomes. 
• Ketogenic diet is sometimes used in treatment for refractory spasms.

Treatment Timeline

1. Diagnose, usually in the inpatient setting
2. Follow-up at 1 week
   1. Have spasms resolved? -> continue treatment
   2. Have spasms continued? -> escalate or change treatment
3. Obtain EEG at week two and a month after the steroid wean is completed to assess for reemergence of spasms or hypsarrhythmia. Other underlying abnormalities could suggest future epilepsy risk  
4. For patients who get treatment and have a normal EEG without recurrence of spasms, they are followed for 1-2 years and if doing well could discharge from Neurology follow-up.

Prognosis

• It is important to emphasize to families that they have done the right thing by seeking care and doing everything possible to get their child the best outcome
• Underlying etiology drives prognosis in terms of developmental outcomes and future epilepsy risk; therefore, Dr. Catenaccio often reserves very optimistic or pessimistic counseling until we have a known etiology
  • Expert opinion: children with idiopathic infantile spasms may have the best developmental outcomes. She generally counsels families not to be frustrated if nothing is seen on MRI or on genetic testing.
• Kids who were developmentally appropriate prior to onset of spasms tend to do better.
• Only around 20-25% of patients with infantile spasms have normal or near normal development and will not go on to develop future epilepsy

Health Disparities

• Underserved populations have worse outcomes related to diagnostic lag and not receiving standard first line therapies (Ann Neur, 2023)
• Prednisolone is very inexpensive and can be feasible even for an uninsured patient. Vigabatrin is usually covered by insurance given that infantile spasms is the FDA indication.
• In general, infantile spasms is a very underserved area of pediatric neurology as it is not a focus of new drug development. Infantile spasms need to be studied!

Links

https://www.epilepsy.com

https://www.cureepilepsy.org

Goal

Listeners will understand the basic diagnostic schema and management of infantile spasms to improve both recognition and treatment. 

Learning Objectives

After listening to this episode listeners will… 

1. Attain a general sense of concerning vs. not concerning infant neurologic exam and history.
2. Be familiar with the diagnostic criteria of infantile spasms.
3. Feel more comfortable with the trajectory of infantile spasms treatment.
4. Recognize when an EEG is indicated for an unusual infant movement, and identify hypsarrhythmia as the characteristic finding.
5. Compare first-line treatment options for infantile spasms — prednisolone, ACTH, and vigabatrin — including when each is favored.
6. Appreciate why early, effective treatment matters and how rapid sequential therapy guides escalation when spasms persist.
7. Understand how underlying etiology drives developmental and epilepsy-risk prognosis.

Disclosures

Dr. Catenaccio reports no relevant financial disclosures. The Cribsiders report no relevant financial disclosures. 

Citation

Fan J, Catenaccio E, Chiu C, Masur S. “#188  On Infantile Spasms and Seizures”. The Cribsiders Podcast. https:/www.thecribsiders.com/ August 12th, 2026.